Walking for subjects with type 2 diabetes: a systematic review and joint AMD/SID/SISMES evidence-based practical guideline

Aims

Regular exercise is considered a cornerstone in the management of type 2 diabetes mellitus (T2DM). It improves glucose control and cardiovascular risk factors, contributes to weight loss, and also improves general well-being, likely playing a role in the prevention of chronic complications of diabetes. However, compliance to exercise recommendations is generally inadequate in subjects with T2DM. Walking is the most ancestral form of physical activity in humans, easily applicable in daily life. It may represent, in many patients, a first simple step towards lifestyle changes. Nevertheless, while most diabetic patients do not engage in any weekly walking, exercise guidelines do not generally detail how to improve its use. The aims of this document are to conduct a systematic review of available literature on walking as a therapeutic tool for people with T2DM, and to provide practical, evidence-based clinical recommendations regarding its utilization in these subjects.

Data synthesis

Analysis of available RCTs proved that regular walking training, especially when supervised, improves glucose control in subjects with T2DM, with favorable effects also on cardiorespiratory fitness, body weight, and blood pressure. Moreover, some recent studies have shown that even short bouts of walking, used for breaking prolonged sitting, can ameliorate glucose profiles in diabetic patients with sedentary behavior.

Conclusions

There is sufficient evidence to recognize that walking is a useful therapeutic tool for people with T2DM. This document discusses theoretical and practical issues for improving its use.

Walking for subjects with type 2 diabetes: A systematic review and joint AMD/SID/SISMES evidence-based practical guideline

AIMS

Regular exercise is considered a cornerstone in the management of type 2 diabetes mellitus (T2DM). It improves glucose control and cardiovascular risk factors, contributes to weight loss, and also improves general well-being, likely playing a role in the prevention of chronic complications of diabetes. However, compliance to exercise recommendations is generally inadequate in subjects with T2DM. Walking is the most ancestral form of physical activity in humans, easily applicable in daily life. It may represent, in many patients, a first simple step towards lifestyle changes. Nevertheless, while most diabetic patients do not engage in any weekly walking, exercise guidelines do not generally detail how to improve its use. The aims of this document are to conduct a systematic review of available literature on walking as a therapeutic tool for people with T2DM, and to provide practical, evidence-based clinical recommendations regarding its utilization in these subjects.

DATA SYNTHESIS

Analysis of available RCTs proved that regular walking training, especially when supervised, improves glucose control in subjects with T2DM, with favorable effects also on cardiorespiratory fitness, body weight and blood pressure. Moreover, some recent studies have shown that even short bouts of walking, used for breaking prolonged sitting, can ameliorate glucose profiles in diabetic patients with sedentary behavior.

CONCLUSIONS

There is sufficient evidence to recognize that walking is a useful therapeutic tool for people with T2DM. This document discusses theoretical and practical issues for improving its use. This article is co-published in the journals Sport Sciences for Health and Nutrition, Metabolism and Cardiovascular Diseases.

Recurrence quantification analysis of heart rate variability during continuous incremental exercise test in obese subjects

The present paper concerns a new description of changing in metabolism during incremental exercises test that permit an individually tailored program of exercises for obese subjects. We analyzed heart rate variability from RR interval time series (tachogram) with an alternative approach, the recurrence quantification analysis, that allows a description of a time series in terms of its dynamic structure and is able to identify the phase transitions. A transition in cardiac signal dynamics was detected and it perfectly reflects the aerobic threshold, as identified by gas exchange during an incremental exercise test, revealing the coupling from the respiratory system toward the heart. Moreover, our analysis shows that, in the recurrence plot of RR interval, it is possible to identify a specific pattern that allows to identify phase transitions between different dynamic regimes. The perfect match of the occurrence of the phase transitions with changes observed in the VO₂ consumption, the gold standard approach to estimate thresholds, strongly supports the possibility of using our analysis of RR interval to detect metabolic threshold. In conclusion, we propose a novel nonlinear data analysis method that allows for an easy and personalized detection of thresholds both from professional and even from low-cost wearable devices, without the need of expensive gas analyzers.

Effects of an individualized home-based unsupervised aerobic training on body composition and physiological parameters in obese adults are independent of gender

PURPOSE

Evaluation of the effects of an individualized home-based unsupervised aerobic training on body composition, physical and physiological parameters in female and male obese adults.

METHODS

Two hundred and twenty obese adults (age 47.9 ± 12.4 years; BMI 38.0 ± 7.2 kg/m²) entered the 4-month training program. Body composition, physiological and functional capacities were assessed pre- and post-intervention. All subjects were requested to perform unsupervised aerobic training with the intensity based on heart rate, walking speed and OMNI-RPE score corresponding to the individual ventilatory threshold for at least 5 days/week.

RESULTS

After 4-month study period, 40% of patients completed the protocol, 24% had high compliance (HC) (exercise ≥ 3 days/week), while 16% had low compliance (LC) to exercise prescription (exercise < than 3 days/week). In HC group, a significant improvement of body composition variables after training was performed. Moreover, oxygen uptake and metabolic equivalent at peak significantly increased after training. Six-minute walking test (6MWT) distance significantly increased while heart rate during 6MWT was significantly lower after training. No significant differences were found in LC group between pre- and post-intervention in all variables. Interestingly, gender does not influence the effects of training.

CONCLUSIONS

Our results indicate that subjects, independent of gender, with high compliance to the aerobic training based on a new individualized method can achieve a significant reduction in weight loss and also an improvement in physical and physiological parameters. This innovative personalized prescription could be a valuable tool for exercise physiologist, endocrinologists, and nutritionists to approach and correct life style of obese subjects.

Acute physical activity and delayed attention in primary school students

To examine the influence of different types of exertion on immediate and delayed attention in 116 primary school children divided in three groups of exertion [cognitive exertion - CE (school curricular lesson), physical exertion - PE (traditional physical education lesson), mixed cognitive and physical exertion - CPE (coordinative physical education lesson)]. CPE was the combination of physical load due to the practice of physical exercises and of cognitive load requested to perform movement-based problem solving tasks requiring accurate timing, temporal estimations, temporal production, and spatial adjustments. Children's attentional capacity was tested before (pre) and after (at 0 min and at 50 min post) a CE, a PE, or a CPE lesson, using the d2-test of attention, and analyzed using a 3 × 3 × 2 mixed analysis of covariance with exertion type and time as within factors, gender as between factor, and baseline data as covariate. Effect sizes were calculated as partial eta squared (ƞ(2)). Results showed that participants' attentional performance was significantly affected by exertion type (P < 0.0001), by time (P < 0.0001) and by exertion type × time interactions (P < 0.0001). The effect sizes ranged from medium (0.039) to large (0.437). Varying the type of exertion has different beneficial influences on the level of attention in school children.

Testosterone responses to standardized short-term sub-maximal and maximal endurance exercises: issues on the dynamic adaptive role of the hypothalamic-pituitary-testicular axis

BACKGROUND

Few and conflicting data on the acute adaptive role of the hypothalamic-pituitary-testicular (HPT) axis to sub-maximal endurance exercise exist.

AIMS

To investigate the acute HPT axis responses to standardized endurance exercises in a laboratory setting and the correlations between testosterone and classic adaptive hormones variations.

SUBJECTS AND METHODS

12 healthy male volunteers were recruited for this experimental study. Serum PRL, GH, ACTH, LH, cortisol, DHEAS, testosterone [total (TT), calculated free (cFT) and bioavailable (cBioT)], SHBG, and respective ratios, were evaluated before and after a 30-min sub-maximal exercise on cycle ergometer at individual anaerobic threshold (IAT) and a maximal exercise until exhaustion. Blood samples were collected before exercise (30, 15 min and immediately before), immediately after and at different time points during recovery (+15, +30 and +60 min) for hormones assays. Oxygen consumption and lactate concentration were evaluated.

RESULTS

Testosterone (TT, cFT and cBioT) acutely increased in all volunteers after both exercises. Testosterone increased in parallel to GH after both exercises and to cortisol only after maximal exercise. Differently from other increased hormones, testosterone increases were not correlated to exercise-intensity-related variables. The anabolic/catabolic steroids ratios were higher after sub-maximal exercise, compared to maximal.

CONCLUSIONS

A 30-min sub-maximal endurance exercise acutely increased serum testosterone similarly to maximal exercise, but without cortisol increases. Exercise-related testosterone peaks should be considered adaptive phenomena, but few data on their short- and long-term effects exist. Investigations on the mechanisms of adaptation to exercise in active individuals with physiological or pathological hypo-testosteronemia are warranted.

Exercise intensity and gender difference of 3 different salsa dancing conditions

The aims of this study were to estimate the difference in exercise intensity (METs), energy cost (EE) and gender difference between a typical salsa lesson (TSL), rueda de casino lesson (RCL), and salsa dancing at a night club (SDN). Subjects performed 1 pre-testing session and 3 testing conditions. During the pre-testing session height, weight and V˙O2max were assessed. During the testing conditions all subjects performed 3 different kinds of salsa dance. Heart rate was assessed during each dance condition. The exercise intensity of the 3 salsa dancing conditions was moderate ranging from 3.9 to 5.5 METs. A significant difference between genders for HRpeak (P=0.01), max%HRR (P=0.006) and mean EE (P=0.02) were observed. Significant gender×condition interactions for HRpeak (P=0.03), mean %HRR (P=0.02), mean METs (P=0.02) and mean EE (P=0.02) were found. In addition, a significant main effect for each condition was found in all variables (P<0.01). Our results showed that the exercise intensities of all 3 salsa dancing conditions were moderate. Findings showed some significant differences in exercise intensity between males and females and within conditions. Salsa dancing could be useful in achieving a significant training effect in people who have a low level of fitness.

EMG patterns during running: Intra- and inter-individual variability

Rectified surface electromyographic (EMG) patterns of five healthy, young, physically-fit subjects running at 4.2 m s(-1) on a treadmill were recorded with the objective of defining a normal profile of EMG activity for running gait. This knowledge is important in understanding how the central nervous system (CNS) controls simple running tasks under normal conditions. The EMG signals from seven muscles (erector spinae, rectus femoris, vastus medialis, vastus lateralis, biceps femoris, tibialis anterior and gastrocnemius) were recorded, together with footswitch signals. The intra- and inter-individual variability of each muscle's EMG profile and peak times were analysed. Interindividual EMG peak time values were analysed to define the timing of the activity of the muscles studied relative to the stride cycle and its subphases. For each muscle, little variation was found within individuals in EMG profile and peak time across trials, but differences between subjects were significant (P < 0.01). EMG peak time analysis showed two distinct activation sequences of different muscles: the first at stance phase and the second at terminal swing. In conclusion, in spite of a significant variability among subjects in EMG profile and peak time values for each muscle, the EMG peak timing analysis showed a sequence of activation at stance phase, no EMG peak activity during the first double swing and another sequence of activation during terminal swing. These findings are evidence of a neuromuscular control strategy common to all subjects.

Effects of music during exercise in different training status

AIM

This study examined the interaction of exercise and music to establish the impact of these factors on state-anxiety and time to exhaustion comparing trained and active participants.

METHODS

Twenty-six university students (13 trained, 13 active) completed the State-anxiety Inventory questionnaire before and after a submaximal treadmill running until volitional exhaustion in both music and no-music condition.

RESULTS

ANOVA showed that both trained and active groups significantly reduced their State-Anxiety scores after exercise tasks (P<0.01, partial η2=0.26) independently by the presence of music. Finding also revealed that active group reported a higher significant reduction of their state anxiety score after exercise in music condition compared to no-music task (P<0.05, d=0.80), while this effect in trained group was not significant. Moreover, data showed that only active-subjects significantly prolonged their exercise experience in presence of music (P<0.05, d=0.47), while trained group did not.

CONCLUSION

This study supports the general finding that exercise is associated with state-anxiety reduction, and suggests that music during exercise may improve this effect in active but not in trained participants. Further, listening to music during exercise may prolong the participants' exercise experience but different training status seems to qualify differently this response.

Assessing basketball ability in players with mental retardation

BACKGROUND

Although athletes with mental retardation (MR) have achieved an important role, literature concerning the evaluation tests in basketball is still poor.

OBJECTIVE

To assess basketball ability before and after a 4-month training performed before championship for athletes with MR and to correlate ability variations with MR levels.

METHODS

15 trained basketball players with MR (11 men and 4 women; age range 21-43 years; MR: 3 mild, 8 moderate, 8 severe and 1 profound). Athletes were tested before (pre) and after (post) 4 month training preceding the championship. The tests assessed 4 levels of ability, each one characterised by 4 fundamental areas of this game: ball handling, reception, passing and shooting. Each area was divided into 5 specific components.

RESULTS

The team average score, based on the score of each athlete's 4 levels, improved by 6.6 points (41.6 (SD 11.9) vs 48.2 (14.7)). The comparison between pre and post scores in each level showed increases (p<0.01), especially in level II (14.4 (3.5) vs 16.5 (3.3)) and in level III (7.1 (5.7) vs 9.2 (6.6)). Within level II, ball handling (3.67 (1.2) vs 4.37 (0.5); p<0.05) and passing (3.20 (1.2) vs 3.97 (1.3); p<0.01) improved; in level III reception (3.21 (1.1) vs 3.73 (1.1); p = 0.01) and shooting (1.82 (1.1) vs 2.45 (1.3); p<0.05) increased.

CONCLUSIONS

A 4 month training caused a general improvement, especially evident in levels II and III. Total score reached in level II was negatively correlated with MR level (r = -0.56; p<0.05), indicating that athletes with lower MR obtained higher scores.

Leaping ability and body composition in rhythmic gymnasts for talent identification

AIM

Aim of this study was to investigate leaping ability and morphological characteristics in rhythmic gymnastics, in order to verify which parameters are useful indicators for the talent identification.

METHODS

Twenty-five national gymnasts of international level (age 14.7+/-2.2 years) underwent three testing sessions: anthropometric measurements, vertical jumps (counter movement jump and hopping test), and three technical split leaps with stretched legs (SL), with ring (RG) and with back bend of the trunk (BBT).

RESULTS

Elite had significantly different values (P < 0.05) of stature (1.65+/-0.03 vs 1.55+/-0.09 m), thigh length (0.42+/-0.03 vs 0.39+/-0.02 m) and FFM(42.42+/-2.81 vs 35.84+/-5.66 kg) compared to sub-elite. The height of hopping test was significantly higher in elite than sub-elite gymnasts (0.34+/-0.05 vs 0.27+/-0.04 m; P < 0.05), but no significant differences in counter movement jump between two groups were found. Ground contact time of hopping test was significantly correlated (P < 0.01) with SL (r = 0.613), RG (r = 0.632), and BBT (r = 0.542) values. By multiple regression analysis, among anthropometric and vertical jump variables, the hopping ground contact time was the strongest predictor of ground contact time of the three technical leaps (SL, RG, BBT) accounting for 26-37% of variance.

CONCLUSION

Some anthropometric measurements are good indicators for the better performance in rhythmic gymnastics. Level of muscle compliance (stiffness) evaluated by hopping test is a good parameter for athletes selection and for monitoring leaps training.

Is explosive performance influenced by androgen concentrations in young male soccer players?

OBJECTIVE

There is growing interest in the implementation and assessment of strength and conditioning programmes among young children. The purpose of this study was to examine the association between given anthropometric characteristics, pubertal development, salivary androgen hormones and explosive leg power in young soccer players.

METHODS

51 (age range 10-14 years) soccer players were investigated. The relations between age, pubertal developmental stages, testicular volume, weight, height, body fat, fat free mass, salivary DHEAS concentrations, salivary testosterone concentrations and lower limb explosive power were evaluated.

RESULTS

Standing long jump length was positively correlated (p<0.05) with age (11.7 (SD 1.2) years, r = 0.66), pubertal developmental stages (mode and range: 1 (1-4), r = 0.64), testicular volume (8.8 (5.2) ml, r = 0.58), height (1.50 (0.10) m, r = 0.34), weight (43.7 (9.1) kg, r = 0.34), fat free mass (35.4 (7.2) kg, r = 0.67), salivary DHEAS concentrations (4.4 (1.2) ng/ml, r = 0.38) and negatively correlated with body fat (18.6 (7.0) kg; r = -0.49, p<0.05). There was no significant correlation between salivary testosterone concentrations (0.3 (0.1) ng/ml, r = 0.12) and standing long jump.

CONCLUSIONS

Results of the present investigation demonstrated that age, pubertal developmental stages, testicular volume, weight, height, fat free mass, and salivary DHEAS concentrations were associated with standing long jump performance. In addition, salivary testosterone concentrations were not related to explosive leg power. Results of the present investigation suggest that the teacher/coach should evaluate long jump performance relative to the subject's given biological characteristics, and not simply established standards based on chronological age.

The Long-Acting Phosphodiesterase Inhibitor Tadalafil does not Influence Athletes' V·O2max, Aerobic, and Anaerobic Thresholds in Normoxia

Whereas experimental studies showed that in healthy trained subjects, the phosphodiesterase-5 inhibitor (PDE-5i) sildenafil improves exercise capacity in hypoxia and not in normoxia, no studies on the effects of the long half-life PDE-5i tadalafil exist. In order to evaluate whether tadalafil influences functional parameters and performance during a maximal exercise test in normoxia, we studied 14 healthy male athletes in a double-blind cross-over protocol. Each athlete performed two tests on a cycle ergometer, both after placebo or tadalafil (at therapeutic dose: 20 mg) administration. Oxygen consumption (VO2), blood lactate, respiratory exchange ratio, rate of perceived exertion, arterial blood pressure (BP), heart frequency (HR) and oxygen pulse (VO2/HR) were evaluated before exercise, at individual ventilatory and anaerobic thresholds (IVT and IAT), at VO2max and during recovery. Compared to placebo, a single tadalafil administration significantly reduced systolic BP before and after exercise (p < 0.05), decreased VO2/HR at IVT (13.3 +/- 1.8 vs. 14.5 +/- 2.1 mL . beat (-1); p = 0.03), but did not modify individual VO2max, IVT, or IAT. In healthy athletes, 20 mg of tadalafil does not substantially influence physical fitness-related parameters, exercise tolerance, and cardiopulmonary responses to maximal exercise in normoxia; it remains to be verified if higher doses/prolonged use influence health and/or sport performance in field conditions.

Exercise Intensities during a Ballet Lesson in Female Adolescents with Different Technical Ability

To investigate the exercise intensity during a typical grade five ballet lesson, thirty-nine dancers (13 - 16 yrs) were divided into three different technical proficiency groups: low level (n = 13), intermediate level (n = 14), and high level (n = 12). A progressively incremented treadmill test was administered to determine VO(2max), individual ventilatory threshold (IVT), and the individual anaerobic threshold (IAT). Oxygen uptake (VO(2)), heart rate (HR) and blood lactate (La) were then evaluated during a grade five ballet lesson. Oxygen uptake at IVT, IAT and maximal oxygen uptake were greater (p < 0.05) in the high-level dancers indicating a higher level of fitness. HR and %VO(2max) obtained during the various exercises of the ballet lesson were similar among groups. During the ballet lesson, low technical level dancers had more V.O (2) and La values above (p < 0.05) the IAT than the other groups. Correlation analysis revealed that the number of exercises performed above IAT was positively related to anthropometric characteristics (BMI, %FM; r = 0.36, p < 0.05; r = 0.46, p < 0.01), negatively related to fitness parameters (VO(2IVT), VO(2IAT), VO(2max); r between - 0.43 and - 0.69; p < 0.001) and to technical level (r = - 0.70; p < 0.001). The subjects classified as having low technical abilities had lower fitness levels and performed more exercises above IAT than the more skilled dancers.

Effect of tadalafil on anaerobic performance indices in healthy athletes

OBJECTIVE

Given the therapeutic and non-therapeutic use of the tadalafil, (phosphodiesterase-5 inhibitor, PDE-5i), we examined its effects on anaerobic performance indices.

METHODS

In total, 12 well-trained subjects reported to the laboratory on two occasions 1 week apart to perform a 30 s Wingate anaerobic power test (WAnT) on a bicycle ergometer. The day before the WAnT, the subjects were double-blinded to receive an oral dose of tadalafil (20 mg) or placebo. Blood lactate value at rest and 1, 3, 6 and 10 minutes of recovery phase, mean power, peak power, time to peak power and fatigue index were assessed for each WAnT.

RESULTS

Blood lactate values at the 3-min recovery WAnT increased significantly in the tadalafil condition (mean (SD) 13.9 (1.7) v 12.8 (1.3) mmol/l; p<0.05) and time to peak power decreased significantly (6.3 (1.3) v 5.7 (1.5) s; p = 0.05). No differences were observed in any other parameters between the two conditions.

CONCLUSION

The primary finding of this investigation was that the administration of a single dose of a long-term PDE-5i does not substantially influence anaerobic performance indices. However, results demonstrated both an increase in lactate values at the 3-min point of the recovery phase and a decrease in time to peak power.

Slow component of VO(2) during level and uphill treadmill running: relationship to aerobic fitness in endurance runners

AIM

The aim of this study was to compare the oxygen uptake (VO(2)) slow component (SC) during level and uphill running in endurance runners, and to identify associations between the SC and the following aerobic fitness indicators: peak VO(2), running speed associated with the peak VO(2) (Vpeak), running speed at the lactic threshold and the VO(2) fraction elicited at the lactic threshold.

METHODS

Fourteen male endurance-trained runners underwent several 6-min bouts of level (LTR) and 10.5% uphill treadmill running. VO(2) SC was calculated as the difference between mean VO(2) during the 6th and the 3rd minutes.

RESULTS

The highest mean values for the SC were 181.9+/-240.2 mL x min(-1) for level running at approximately 94% peak VO(2)2 and 105.4+/-154.6 mL x min(-1) for uphill running at approximately 90% peak VO(2). The SC observed during the last bout of the LTR correlated with peak VO(2) and with Vpeak (-0.71 and -0.76, P<0.05, respectively).

CONCLUSION

The results show that for endurance-trained runners the magnitude of the SC is not affected by the treadmill gradient and that within a homogeneous sample of endurance-trained runners the SC does not correlate with indicators of aerobic fitness.

Do non-steroidal anti-inflammatory drugs influence the steroid hormone milieu in male athletes?

Prostaglandins modulate the hypothalamus-pituitary-adrenal and -gonadal axis pathways. We explored the effects of a single course of treatment with acetylsalicylic acid (ASA), an inhibitor of prostaglandin synthesis, on the steroid milieu in athletes. Morning plasma cortisol (F), dehydroepiandrosterone sulphate, free-testosterone, testosterone (T) and their ratios were evaluated before and after the administration of either ASA or placebo in twelve male athletes, when affected by minor musculoskeletal trauma and, as control, after a five/six week wash-out in healthy conditions respectively. One tablet of ASA (800 mg), or placebo, was administered two times daily for 10 days during treatment. All the volunteers suspended exercise training during treatment. The results revealed that compared to placebo, plasma F was significantly lower after ASA treatment (p = 0.023). Furthermore, the comparison of hormone's absolute and percentage of variations (Delta and Delta%) between ASA and placebo treatment showed significant differences respectively for DeltaF (p = 0.045), for DeltaT (p = 0.047), for DeltaT/F (p = 0.042), for DeltaF% (p = 0.04) and for DeltaT% (p = 0.049). Our data suggest that in comparison to placebo, a short-term ASA treatment is able to influence the plasma steroid milieu in athletes. Due to the observed variability of the individual hormonal patterns, further research is required to substantiate these findings.

Effect of creatine on swimming velocity, body composition and hydrodynamic variables

AIM

Creatine supplementation (CS) has been reported to increase body weight and improve performance during high intensity, short duration, exercise tasks. However, none of the published studies has investigated the influence of CS on performance related hydrodynamic variables during swimming. To investigate the effect of oral CS on swimming velocity, body composition and hydrodynamic variables during the period of final preparation of competitive junior female swimmers.

METHODS

In a double blind and randomized manner, 16 female swimmers, were supplemented with 20 g day(-1) of creatine monohydrate (CS group), or a maltodextrin placebo (PL group) for 21 days. Just pre- and post-21 days of supplementation, subjects performed 2x25 swimming bouts at maximum velocity with a 3 min recovery between bouts. The variables measured were 25 m swimming velocity (MSV(25)); active drag force (D(f)); hydrodynamic coefficient (C(x)); power output (P(o)). Body measures were also analysed: body weight (kg), fat-mass (% FAT), body water (% H(2)O), and fat free mass (FFM).

RESULTS

Significant differences were observed in hydrodynamic values: the CS group showed a significant reduction (approximately =25%), in D(f), C(x) and P(o) values, when comparing pretest with post-test. No differences were found in variables related to body composition and performance between CS group and PL group, as well as for CS group during the experimental period.

CONCLUSIONS

These data suggest that 21 days of CS produced significant effects on gross and/or propelling efficiency during swimming in female athletes. However, CS did not influence performance, body weight and body composition.

Cortisol, dehydroepiandrosterone sulphate and dehydroepiandrosterone sulphate/cortisol ratio responses to physical stress in males are influenced by pubertal development

To evaluate the influence of chronological age and pubertal development on the hypothalamus-pituitary-adrenal (HPA) axis response to stress, we studied the possible correlations between male pubertal characteristics and salivary cortisol (C), DHEAS and the DHEAS/C ratio before (pre-stress) and after acute exercise-stress in young male volunteers (no. 87; 13.3+/-2.1 yr). In our overall study population, the mean pre-stress salivary C and DHEAS concentrations, significantly increased after exercise-related stress, whereas the DHEAS/C ratio significantly decreased. Pre-stress salivary C was positively correlated with chronological age, and after-stress salivary C concentration variations were negatively correlated with pubertal stage, mean testis volume and pre-stress salivary DHEAS. Furthermore, salivary DHEAS concentrations and the DHEAS/C ratio, before and after exercise stress, were positively correlated with chronological age, pubertal stage, pre-stress salivary testosterone (T), testis volume and body mass index (BMI). In contrast with late pubertal stages (P4, P5), young individuals at early stages of puberty (P1 to P3) showed higher C increase and lower DHEAS/C ratio after exercise-related stress. In conclusion, since C is also a mediator of stress-related negative effects on health and the DHEAS/C ratio has been hypothesized as an index for the degree to which an individual is buffered against the negative effects of stress, these data might suggest potentially increased stress-related risks at early stages of male puberty.

Salivary Steroids at Rest and After a Training Load in Young Male Athletes: Relationship with Chronological Age and Pubertal Development

Puberty influences both the performance and the hormonal responses to exercise-related stress. We evaluated the distribution and the correlation between pubertal characteristics and the salivary cortisol (sC) and testosterone (sT) responses to acute physical exercise in young male athletes (13.4 +/- 2.1 yr, n = 110). The mean pre-exercise nmol . L (-1) sC and sT concentrations were 19.08 +/- 4.32 and 0.34 +/- 0.15 and increased to 21.27 +/- 5.51 and 0.41 +/- 0.16 after a 90-min training session (p < 0.01). The sC concentration at rest was positively correlated with chronological age (p < 0.01) and negatively correlated with fat % (p < 0.05), whereas significant negative correlations of DeltasC and DeltasC% after exercise with age, pubertal stage and mean testis volume (p < 0.05) were observed. The sT increase after exercise was correlated with chronological age, pubertal stage and pre-exercise sT levels (p < 0.01), whereas the DeltasT and DeltasT% of increase were negatively correlated with chronological age and resting sT levels (p < 0.05 and p < 0.01). In the present study, we observed the presence of high inter-individual variability of different biological parameters (anthropometry, pubertal stage, hormones, etc.) within athletes selected by chronological age in the same class and the presence of significant correlations between chronological age, puberty and the steroid hormone responses to physical exercise. Our data suggest the need for different criteria in exercise prescription and selection of young athletes and in the evaluation of stress reactivity at puberty.

[Pilot study on the presence of Legionella spp in 6 Italian cities' dental units]

Among the microorganism involved in environmental contamination, Legionella spp is actually considered an important infectious hazard. The aim of this study is to evaluate the incidence of Legionella spp in water samples collected from 138 dental unit selected from public outpatient clinics of 6 Italian cities. The samples were taken from oral rinsing cup, air-water syringe, ultrasonic scaler and the turbine to investigate Legionella spp, Pseudomonas aeruginosa and the total heterotrophic count at 36 degrees and 22 degrees. Legionella spp was present in 33,3% dental unit water; but a significant difference was shown among the enrolled cities. In 43,5% of water sample Legionella concentration was 1.000-10.000 CFU/L and in 30,4% was >10.000 CFU/L. L. pneumophila 1 was found in 23,9% of water samples. The results demonstrate that the concentration of Legionella spp in dental unit water lines could be high and this suggests that the exposure to these micoorganism during the dental practise could be a potential health risk both for dental personnel and for the patients too, especially when immunocompromised.

Blood lactate removal during recovery at various intensities below the individual anaerobic threshold in triathletes

AIM

Optimal lactate removal was reported to occur at work-rate between 30% and 70% VO2max. However, it has been recently recommended to quantify exercise intensity not in percentage of VO2max but in relation to validated metabolic reference points such as the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT). The purpose of this study was to examine the effect on lactate removal of different recovery work-rates below the IAT defined calculating the difference (DT) between IAT and IVT, then choosing the IVT+50%DT, the IVT and the IVT-50%DT work-rates.

METHODS

Eight male triathletes (VO2max 69.7+/-4.7, VO2IAT 52.9+/-4, VO2IVT 41.1+/-4.7 mL x kg(-1) x min(-1)), after a 6-min treadmill run at 75% of difference between IAT and VO2max, performed in a random order the following 30-min recovery treatments: 1) run at IVT(plus;50%DT), 2) at IVT, 3) at IVT(-50%DT), 4) passive. Blood lactate was measured at 1, 3, 6, 9, 12, 15, 20, 25, 30 minutes of recovery.

RESULTS

All active recovery work-rates (from 50+/-5% to 67+/-4% VO2max) were within the range previously reported for optimal lactate removal, and significantly more efficient than passive recovery on lactate removal curve (% of accumulated lactate above rest value). However, significant differences (P<0.01) were found among active recovery intensities: the IVT(-50%DT) was the most efficient work-rate from the 9th minute to 30th minute.

CONCLUSIONS

In triathletes, the IVT(-50%DT) was the optimal work-rate for lactate removal; moreover none of the studied active work-rate showed further lactate decrease after the 20th minute of recovery.

Heredity and Pituitary Response to Exercise-Related Stress in Trained Men

To evaluate the role of heredity in the pituitary responses to exercise-related stress, serum ACTH, beta-endorphin, cortisol, GH, and PRL responses to a thirty-minute treadmill exercise at individual anaerobic threshold were evaluated in nine pairs of male monozygotic twin athletes. Hormone evaluations were performed before (-30, -15, 0 pre) and after exercise (0 post, + 15, + 30, + 45, + 60, and + 90 min). The intraclass correlation coefficient (expression of within-pair resemblance) was computed for each hormone before and after exercise as area under curves (AUC), absolute values, and percentage of variation, respectively. The exercise-related stress condition induced a significant increase for all evaluated hormones before (anticipatory response) and/or after exercise. As new data, we observed: 1) A significant within-pair resemblance for exercise-related GH and PRL increase (AUCs and/or absolute values), and for the percentage of variation of cortisol, and 2) the lack of significant resemblance for the observed increase of ACTH, cortisol and absolute beta-endorphin serum concentration. This first co-twin control study supports the hypothesis that, in trained men, there are probably different relative roles for the influence of genetic factors on the pituitary hormones involved in physiological adaptation to exercise-related stress. Furthermore, our findings justify further investigations into this topic.

Physiological factors in middleweight boxing performance

BACKGROUND

We examined, within the middleweight class, the relationship between ranking in boxing competition performance and some physiological factors.

METHODS

Eight elite Italian amateur boxers (first series of AIBA ranking) were assessed in 2 testing sessions, a week apart. In the first testing session all subjects underwent anthropometric measurements from which body fat percentage, upper arm and forearm muscle cross-sectional areas were estimated. In the second testing session all subjects performed grip strength measures and a maximal treadmill test to assess oxygen consumption (VO2), blood lactate and heart rate at maximal effort, at individual anaerobic threshold, and at individual ventilatory threshold. The athletes were ranked following the criteria of world amateur AIBA ranking. In this ranking the first ranked boxer had the highest score gained participating in international tournaments.

RESULTS

A Spearman rho correlation analysis revealed that the VO2 at individual anaerobic threshold (46.0+/-4.2 ml x kg(-1) x min(-1), r=0.91) and the hand-grip strength (58.2+/-6.9 kg, r=0.87) were highly related (p<0.01) to boxing competition ranking. VO(2max) (57.5+/-4.7 ml x kg(-1) x min(-1), r=0.81) and wrist girth (17.6+/-0.6 cm, r=0.78) were moderately (p<0.05) related.

CONCLUSIONS

These data suggest that there are two basic factors related to boxing performance: physical fitness as indicated by individual anaerobic threshold and maximal oxygen consumption, and upper-body muscular strength as indicated by hand-grip strength.

Physical stress and qualitative gonadotropin secretion: LH biological activity at rest and after exercise in trained and untrained men

Sports influence the hypothalamus-pituitary-gonadal axis (HPG). The purpose of this study was to analyze the effects of physical stress on qualitative male LH secretion. We evaluated the HPG axis at rest and the LH response to a treadmill exercise (90 % of Vdot;O 2 max) in eight trained (running 50 to 70 km/week) and eight untrained subjects. FSH, total testosterone (T) and free testosterone (FT) were evaluated at rest by radioimmunoassay, whereas serum LH was evaluated both by radioimmunoassay (I-LH) and by a biological assay (RICT, B-LH), before (-30, -15, 0 pre) and after exercise (0 post, + 15, + 30, + 60 min). Semen analysis was performed. The results showed that the B/I LH ratio was significantly lower at rest in athletes than in controls (1.3 +/- 0.5 and 2.1 +/- 0.7 respectively, p < 0.05) and the B-LH and B/I LH ratio were reduced after exercise in controls (from 21.1 +/- 5.7 to 13.9 +/- 3.4 mIU/mL and from 2.3 +/- 0.8 to 1.6 +/- 0.4, at + 60 respectively, p < 0.05). T and FT were significantly lower in athletes compared with controls (4.18 +/- 1.1 vs 5.96 +/- 1.6 ng/ml and 24.3 +/- 4.8 vs 29.7 +/- 5.2 pg/ml respectively, p < 0.05). Semen parameters showed no difference. The B/I LH ratio could be a "marker" of altered LHRH secretion due to an exercise-linked adaptive condition.

Acetylsalicylic acid inhibits the pituitary response to exercise-related stress in humans

PURPOSE

Prostaglandins (PGs) modulate the activity of the hypothalamus-pituitary axis, and pituitary hormones are largely involved in the physiological responses to exercise. The purpose of this study was to analyze the effects of acetylsalicylic acid (ASA), an inhibitor of PGs synthesis, in the pituitary responses to physical stress in humans.

METHODS

Adrenocorticotropin (ACTH), beta-endorphin, cortisol, growth hormone (GH), and prolactin (PRL) responses to exercise were evaluated after administration of either placebo or ASA. Blood samples for hormone evaluations before (-30, -15, and 0 pre) and after (0 post, +15, +30, +45, +60, and +90 min) a 30-min treadmill exercise (75% of .VO(2max)) were taken from 12 male athletes during two exercise trials. One tablet of ASA (800 mg), or placebo, was administered two times daily for 3 d before and on the morning of each exercise-test.

RESULTS

The results clearly show that, compared with placebo, ASA ingestion significantly blunted the increased serum ACTH, beta-endorphin, cortisol, and GH levels before exercise (anticipatory response) and was associated with reduced cortisol concentrations after exercise. Furthermore, although no differences in the GH response to exercise were shown, a significantly reduced total PRL response to stress condition was observed after ASA.

CONCLUSION

ASA influences ACTH, beta-endorphin, cortisol, GH, and PRL responses to exercise-related stress in humans (preexercise activation/exercise-linked response). Even though it is not possible to exclude direct action for ASA, our data indirectly confirm a role of PGs in these responses. We have to further evaluate the nature of the preexercise endocrine activation and, because of the large use of anti-inflammatory drugs in athletes, whether the interaction between ASA and hormones might positively or negatively influence health status, performance, and/or recovery.

VO2max, ventilatory and anaerobic thresholds in rhythmic gymnasts and young female dancers

BACKGROUND

This study examines the fitness level of a rhythmic gymnasts group and a young female classical dancers group.

METHODS

Aerobic power (VO2max), individual ventilatory (IVT) and anaerobic thresholds (IAT) were assessed in 12 elite rhythmic gymnasts, eight elite ballet dancers and 12 sedentary female subjects in the same age range (13-16 yrs). The VO2max, IVT and IAT were assessed during a continuous incremental running treadmill test.

RESULTS

At IVT and IAT the VO2max expressed in ml x kg(-1) x min(-1) was significantly different between the three groups of subjects. The highest values were found in gymnasts (30.8+/-2.6 for IVT and 43.8+/-3.5 for IAT) followed by the values of dancers (21.7+/-2.8 for IVT and 30.5+/-3.1 for IAT) and controls (15.6+/-2.0 for IVT and 20.6+/-1.7 for IAT). When the VO2max was expressed in percent of VO2max, the values at IAT were significantly different between all groups (gymnasts: 84.9+/-0.7; dancers: 64.0+/-4.1; controls: 59.7+/-2.4) while at IVT no difference was found between dancers and controls (45.6+/-4.1 and 45.2+/-16, respectively). At maximal effort VO2 was significantly higher both in gymnasts and dancers (51.7+/-4.4 and 47.5+/-3.0 ml x kg(-1) x min(-1), respectively), than in controls (34.5+/-2.5 ml x kg(-1) x min(-1)).

CONCLUSIONS

Although VO2max was similar between gymnasts and dancers, VO2 values at NT and IAT were able to discriminate the higher level of fitness in gymnasts with respect to dancers.

Heart rate and match analysis in pre-pubescent soccer players

The aim of this study was to compare match analysis (using video recordings) and the physiological load (heart rate measured every 5 s, blood lactate measured after the warm-up, first half and second half) of six 11-year-old soccer players during official games of eleven-a-side on a regular-sized pitch (100 x 65 m) and of seven-a-side on a smaller pitch (60 x 40 m). In both games, heart rate exceeded 170 beats x min(-1) 84% of the time, while blood lactate ranged from 1.4 to 8.1 mmol l(-1). No significant differences were recorded for the physiological parameters. For both matches, walking comprised 38% of total time, running 55%, inactivity 3% and jumping 3%. Although there were no significant differences between halves or matches, running for less than 10 s was 10% more frequent in the seven-a-side game. In the seven-a-side game, there were significantly more passes and significantly fewer tackles, suggesting that seven-a-side matches played on smaller pitches may be more suitable for pre-pubescent soccer players.

Acute effect of physical exercise on serum insulin-like growth factor-binding protein 2 and 3 in healthy men: role of exercise-linked growth hormone secretion

The purpose of this study was to delineate the role of GH on serum IGF-I, IGFBP-2 and -3 responses to exercise. Hormones were evaluated in six trained male subjects before (-30, -15, 0), during (+15) and after (+30, +45, + 60, +90 min) a thirty-minutes treadmill exercise (60% VO2max), both after a single administration of a somatostatin analog (i.e., octreotide, 0.1 mg sc) and after saline. The same evaluations were performed without exercise with similar treatments. The results showed that: 1) octreotide significantly inhibited the GH response to exercise, 2) exercise increased IGFBP-3 concentration (+37.4% at +90, p < 0.05), whereas no modification of IGFBP-2 and of IGF-I/ IGFBP-2 and IGFBP-3/IGFBP-2 ratios were observed, 3) octreotide amplified the IGFBP-3 increase after exercise (p < 0.01 vs. exercise, from + 30 to + 60, or octreotide alone) and, without exercise, slightly increased IGFBP-3 (+15% at +75, p < 0.05) and decreased IGF-I (-14.8% at +75, p < 0.01). We concluded that GH has a reduced role, as a stimulating factor, in the serum acute IGFBP-3 increase after exercise and that octreotide is probably able to directly amplify this response. Unfortunately, we can only speculate on the physiological pathways involved.

A simple method for individual anaerobic threshold as predictor of max lactate steady state

BACKGROUND

The individual anaerobic threshold (IAT) is defined (18) as the highest metabolic rate where blood lactate (La) concentrations are maintained at a steady-state during prolonged exercise. Stegmann et al.'s (18) method to detect IAT, using La-performance relationship during incremental graded exercise, is based on the assumption that La is in relatively steady state by the end of each 3-min stage of work rate. However, at the end of a 3-min stage, an La steady state (Lass) is not reached (13).

PURPOSE

The present study was designed to investigate whether the IAT should be determined by attributing La value to the antecedent stage (IATa) or to the same stage of its measurement (IATm), then to verify whether this IAT would be a valid indicator of the max Lass during prolonged exercise.

METHODS

Forty-one athletes (21 male and 20 female), regularly involved in different physical training, performed three exercise tests on treadmill. The first one was a 3-min stage incremental test to detect the IATa and IATm. The other two tests were 30-min prolonged tests at the IATa and IATm workload. Lass were present in IATa intensity (about 4.0 mmol x L(-1)) both in male and female athletes, whereas at IATm intensity a Lass was not present and a premature break-off occurred in some cases.

DISCUSSION

This protocol can be useful for practical use because: 1) the method of choosing the anaerobic threshold is easy to apply; 2) it does not require to reach the maximal effort; and 3) although in some cases the IATa could probably underestimate the workload of max Lass, the IATa can be regarded as guideline to define the intensity of endurance training.

Energy cost and energy sources of ball routine in rhythmic gymnasts

The energy cost and the different energy sources of competitive rhythmic ball-routines were assessed in nine young elite rhythmic gymnasts (13-16 years of age). The overall energy requirement of ball exercise (VO2eq) was obtained by adding the amount of VO2 during exercise above resting (VO2ex) to the VO2 up to the fast component of recovery (VO2al) and to the energy equivalent of peak blood lactate accumulation (VO2la-) of recovery. The lactate (La) curve up to 25 minutes of recovery always showed La peaks at 3 min after exercise (4.0 +/- 0.4 mmol/l) and values still above rest at 25 min (2.3 +/- 0.5 mmol/l). Although ball routines were short in duration (90 s), the metabolic power requirement was 1.1 times higher than the subject's VO2max. The energy cost (VO2eq) amounted to 81 +/- 5 ml x kg(-1). Higher fractions of VO2eq were VO2ex 49% and VO2al 42%, while the remaining 9% was due to VO2la-. The aerobic source resulted in the most utilized system due to the subjects' high VO2max (52.7 ml x kg(-1) x min(-1)) and anaerobic threshold (LT = 84.4%). The HR and the peak lactate values of ball routine were similar to the values recorded at LT step during treadmill test. Although the HR and VO2 values were significantly correlated (during pre-exercise, exercise, and fast recovery), the exercise intensity derived from HR Kanvonen method during ball routine did not correspond to the % of VO2max.

Aspirin inhibits androgen response to chorionic gonadotropin in humans

Eicosanoids play an important role in the regulation of the hypothalamic-pituitary axis; less clear is their role in testicular steroidogenesis. To evaluate the involvement of cyclooxygenase metabolites, such as prostaglandins, in the regulation of human testicular steroidogenesis, we examined the effects of a prostaglandin-blocker, aspirin, on plasma testosterone, pregnenolone, progesterone, 17OH-progesterone, androstenedione, dehydroepiandrosterone, and 17beta-estradiol response to human chorionic gonadotropin (hCG) in normal male volunteers in a placebo-controlled, single-blinded study. To test the efficacy of aspirin, seminal prostaglandin E(2) levels were also determined. hCG stimulation increased peripheral levels of testosterone, 17OH-progesterone, androstenedione, dehydroepiandrosterone, and 17beta-estradiol, without affecting circulating pregnenolone and progesterone values. Aspirin significantly lowered seminal prostaglandin E(2) levels, whereas it did not modify steroid concentrations not exposed to exogenous hCG. Moreover, the drug significantly reduced the response of testosterone, 17OH-progesterone, androstenedione, and dehydroepiandrosterone to hCG, as assessed by the mean integrated area under the curve, whereas it did not influence 17beta-estradiol response. In conclusion, aspirin treatment inhibits androgen response to chorionic gonadotropin stimulation in normal humans. The action of aspirin is probably mediated via an effective arachidonate cyclooxygenase block.

Acute amino acids supplementation enhances pituitary responsiveness in athletes

PURPOSE

The purpose of this study was to determine the effect of a mixture of amino acids on pituitary responsiveness to a stimulation test (GnRH + CRH) in athletes.

METHODS

In a double blinded counterbalanced experimental protocol, 10 moderately trained male athletes performed the pituitary stimulation test 60 min after a single oral administration of a placebo (P1-AS) or an amino acid mixture solution (AS) (L-arginine hydrochloride 100 mg x kg(-1) + L-ornithine hydrochloride 80 mg x kg(-1) + L-branched chain amino acids 140 mg x kg(-1): 50% L-leucine, 25% L-isoleucine, 25% L-valine) on two different occasions. Plasma ACTH, LH, FSH, GH, and cortisol were evaluated before (-60, -30, 0 min) and after (+15, +30, +45, +60, +90 min) the stimulation test.

RESULTS

The ACTH, LH and FSH response to CRH + GnRH was significantly higher in AS group both as absolute values and area under curve (AUC) values than in P1-AS group. Pre-test and post-test cortisol AUC levels were significantly higher in P1-AS group although a higher percent increase in post-test cortisol was found in AS group. The total GH-AUC was higher in AS group and, as expected, the absolute GH concentrations at different time points were not influenced by CRH + GnRH administration.

CONCLUSION

The amino acid mixture used enhanced the ACTH, LH, and FSH response to CRH + GnRH.

Growth hormone and insulin-like growth factor I responses to moderate submaximal acute physical exercise in man: effects of octreotide, a somatostatin analogue, administration

We evaluated growth hormone (GH) and insulin-like growth factor I (IGF-I) response to moderate submaximal acute short-term physical exercise under basal conditions and after the administration of octreotide, a somatostatin analogue (SA), in a double-blind, counter-balanced experimental protocol. Seven untrained male volunteers performed two identical exercise tests, each on a treadmill (2.5% slope) for 30 minutes (min) at 60% of VO2max. Before starting the exercise test all the subjects received a single administration of placebo or octreotide and vice versa at two different sessions. Plasma GH, IGF-I and lactate assays were evaluated before starting, during, at the end and in the recovery phase. In the placebo-treated group GH rose significantly both during exercise and recovery whereas no significant modifications in IGF-I levels were observed. SA administration inhibited the exercise-dependent GH secretion, which showed a small rise only during exercise and returned to basal levels during recovery. In the same group, IGF-I decreased significantly after exercise compared to basal values. The results suggest that 1) in our experimental conditions acute physical exercise at aerobic threshold does not modify IGF-I concentration 2) SA is able to inhibit the exercise-dependent GH secretion and to decrease post-exercise IGF-I concentration.

Heart rate, alveolar gases and blood lactate during synchronized swimming

Heart rate, alveolar gas partial pressures and blood lactate (BLa) concentration were measured during synchronized swimming in six subjects. During upside-down breath-holding lasting 50 s, heart rate fell progressively from 98 +/- 14 to 70 +/- 7 beats min-1 (mean +/- S.D.). While breath-holding during the compulsory figures, the subjects' heart rate increased to 142 +/- 5 beats min-1 and then fell to 72 +/- 10 beats min-1. At the end of breath-holding, alveolar oxygen pressure had fallen significantly (60 mmHg), whereas alveolar carbon dioxide pressure showed only minor changes (48 mmHg). The increase in BLa concentration due to the execution of compulsory figures was approximately 1 mM; in the free routines, BLa concentration increased by 3.4 +/- 0.5 mM. The net energy cost of completing a compulsory figures lasting 45 s was 34.6 kJ.

Assessment of static balance in children

The ability in maintaining body balance of 6-, 8-, and 10-year-old children performing three balance tests on a force platform was studied. Thirty adult subjects served as a reference group. The mean radius (MR) of the posturogram and the mean speed (MS) of the center of foot pressure (COP) were used as the measuring parameters. Data were analyzed using two-way ANOVA, the Sheffe test and the Student "t" test with a .05 level of significance. A decrease with age in both mean radius and mean speed, indicating an increase in balance ability, was noted. A significant age main effect was found on all tests while significant gender main effect occurred only on the Tandem test. No significant age/sex interaction was found. Significant differences between the 10-year-old and adult groups occurred only in the more difficult balance tests.

[A pertinent example of the use of public health laboratories in the control of environmental hygiene]

In this communication the work about the Lake Maggiore waters were described like a good example of hygienic environment control. This work carried out in the Medical Department of Novara Public Health Laboratory.